	function fwdcalc(unitchoice,sex,weight,pna,dna){

	
	var fwd=0;
	var tbw=0.6;
	

if (!unitchoice){
weight=weight/2.20462262185;
}	
	
if (sex==0) 
{
tbw = 0.5;
}


//Free Water Deficit = 
// Total Body Water * ((Current Serum Na/Desired Serum Na)-1) * weight in kg (TBW = 0.6 if male and 0.5 if female)
fwd = tbw * ((pna/dna)-1) * weight;

//round to 2 dec places
//gfr=Math.round(gfr*100)/100;
fwd=Math.round(fwd*100)/100;
weight=Math.round(weight*100)/100;
sodium=pna;
			


return {
			 fwd:fwd,
			 weight:weight,
			 sodium:sodium

	};		 
}




function ref(){
// display reference
 return "Merck Manual on <a href='http://www.merck.com/mmpe/sec12/ch156/ch156e.html'>Hypernatremia</a>";

}